Insulated wire



J .-=31,1933. V w s. RUBEN 1,896,042

INSULATED WIRE Filed Aug. 15, 1931 I Inventor P m \I Attorney Patented Jan. 31, 1933 UNITED STATES PATENT OFFICE SAMUEL RUBEN, 01' NEW ROCIELLE, NEW YORK, ASSIGNOB, TO vma MANUFACTURING CORPORATION, OF wnumo'ron, DELAWARE, A CORPORATION OI DELAWARE INSULATED WIRE Application filed August 15, m1. Seriai in. 557,888.

This invention relates to an improved type of insulated wire.

An object of the invention is to produce a wire having a flexible refractory insulation. 5 A further object is the provision of a wire having a closely applied flexible insulating coating containing refractory inorganic material unaffected by hightemperatures.

Another object is the provision of a wire having a refractory insulatingicoating which is resistant to moisture and abrasion.

Other objects will be apparent from the description of the invention and from the drawing in which is shown an insulated wire made in accordance with the invention.

Thisapplication is a continuation in part of my applications filed December 3, 1930, Serial Numbers 499,845 and534,711 of May 2,- 1931. As stated in those applications, I

have foundthat in order to properly coat a wire with an insulating material having the desired characteristics it is desirable also to have 1) a flexible binder of the resinous type to give a proper bond at low temperature and (2) a further binder, which material is to be effective at high temperature; this binder must be of the inorganic type such as boric acid or lead borate. This second and most important binder serves two purposes; one,

.30 it binds the refractory and insulating material at high temperature; two, it prevents scaling and undesirable surface oxidation. In the aforementioned applications I described a coating comprising generally a refractory metallic compound, a or resinous binder and a borate or 0t or inorganic relatively high temperature binding agent. In the present invention, the organic binder or'carrier is distinguished particularly by the fact that to the usual tung oil varnishes or enamels which I have heretofore used as a carrier, I add a phenolic condensation product such as an oil-reactive phenolic'resin, produced by the combination of phenols and formaldehydes. i

The insulating or refractory material used in the insulating coating of this invention, consists of one or more-of the insulating metal or metalloid com ounds, which include the oxides, borates, silicates, and in some cases nickel, copper, zinc, molybdenum, tungsten,

lead, thorium, zirconium. Where the borates, silicates or hydroxides of these elements form insulating compounds, these may be used. Mixtures containing more than one compound, for example, beryl or mica, can also 05 be used in combination or otherwise. The preferred secondary binder is boric acid although other borates may be used. The materials used should be ground to as fine a state as ossible.

e first step in preparation of the coating is the production of the varnish or enamel carrier. Such an enamel I described in my copending application 534,711 and generally it consists of an admixture of synthetic or 76 natural gum type water insoluble resins, drying oils such as tung oil and linseed oil which are heated together, and mineral or naptha thinners.

In the present invention, I add to this 80 enamel a phenolic resinous compound which may preferably be added in the form of a mixture consisting of gallon tung oil, gallon aged raw linseed oil, two pounds of phenolic resin and 80 liquid ounces of mineral spirits, compounded in the following manner; the linseed oil and one pound of the phenolic resin is raised to 560 Fahrenheit in one half hour, held there for 15 minutes and the tung oil and the additional one pound resin then added. The mixture is then raised to 450 Fahrenheit in ten minutes and held to a fairly heavy drip (30-35 minutes). It is thinned direct. For satisfactory results I have found that this phenolic compound may be added to the ordinary tung oil resinous enamel in a proportion of one part of the former to four parts of the latter. However, this is dependent upon the amount of abrasion resistance, elasticity and moisture proofv100 ness desired, the addition of the phenolic resin increasing these qualities according to [61 arately and then add them together, they may also be made as one varnish or enamel by boiling or heating the phenolic resin direct with the usual resinous tung oil varnishes. The phenolic resin has the pro erty of reacting with the drying oils and pro uces, in combination with the refractory material and the boric acid, a tough and adhesive coating. Where a plasticizing agent is desired to increase the flexibility of the coating, I add 1 to 2% of one of the well known plasticizing oils, such as castor oil.

It is recognized, of course, that the borate or secondary binder may be added in the form of a compound with the oil, insulating material or resin, instead of being mixed separately.

A desirable insulating coating is then made by grinding materials in the following proportions: to 450 cc. of the prepared composite enamel, I add 180 grams of iron oxide, (preferably Fe O), 20 grams of chromium oxide, and 100 grams of boric acid, the mixture being milled until the various materials are thoroughly ground' The composition of the coating may be varied by increasing or decreasing the respective amounts of the enamel or of the oxides, depending upon the flexibility or insulation desired. The addition of the boric acid to the mixture is not for the purpose of obtaining a filler but solely to supply a secondary binder and effect a definite reaction between the resinous material and the boric acid. This reaction cannot be ac complished however, unless this mixture is heated to 185 centigrade, at which temperature the boric acid melts and reacts with the resins and other materials. The resultant product, as it appears on the wire, is hard and stable and not affected by humidity or other atmospheric effects. The heat is applied as the coated wire goes through the ovens. I have found that unless the coating be heated to at least 185 centigrade, an impracticable and unstable coating is had which in the course of a few days will disclose on its surface the growth of large horic acid crystals due to absorption of moisture, the

- coating losing flexibility, becoming powder like and readily fracturing off the base. The electrical breakdown potential and insulation will also continuously reduce. But if the coating is heat treated to the melting and reacting point of the boric acid, the foregoing difiiculties are eliminated and no ageing effect is experienced.

A continuous coating process is used in applying the insulation to the wire. The wire passes through cups containing the insulating compound or mixture, being heated and baked in furnaces located between the cups.

During the heating, the inorganic binder, the boric acid, melts and binds the refractory oxide crystals, 9. reat part of the organic materials being ba ed ofi.

- Even though the wire, in use, is heated to a point where the organic binder is disengaged, no harm results due to the presence of the inorganic binder, boric acid. The use of this borate in the coating is also of assistance in dispensing with the necessity of a flux in soldering the wire, particularly when copper wire is coated.

In the accompanying drawing, illustrative of the invention, the copper wire (1) has an insulatin coating thereon consisting of a mixture %1) of an oil phenolic-resin varnish, finely divided refractory oxide and boric acid, baked upon said wire.

I claim:

1. A wire having on its surface a closely adherent layer of flexible refractory insulation consisting substantially of finely divided insulating oxide held upon the wire by an oil phenol-resinous binder.

2. A wire having on its surface a closely adherent layer of flexible refractory insulation in which the refractory material consists substantially of finely divided chromium oxide held upon the wire by an oil phenol-resinous binder.

3. A wire having on its surface a closely ad" herent layer of a flexible refractory insulation consisting substantially of finely divided titanium oxide held upon the wire by an oil phenol-resinous binder.

4:. A wire having on its surface a closely adherent layer of a flexible refractory insulation consisting substantially of finely divided iron oxide held upon the wire by an oil phenol-resinous binder.

5. A wire having on its'surface a closely adherent layer of flexible refractory insulation consisting substantially of the combination of non-fibrous inorganic insulating matter and an inorganic binding material, held upon the wire by an oil phenol-resinous I,

binder.

6. A wire having on its surface a closely adherent layer of flexible refractory insulation consisting substantially of the combination of non-fibrous inorganic insulating matter and a boron compound, held upon the wire by an oil phenol-resinous binder.

7. A wire having on its surface a closely adherent layer of flexible refractory insulation consisting substantially of the combination of finely divided insulating oxide and a boron compound, held upon the wire by an oil phenol-resinous binder.

8. A wire having a flexible insulating coating consisting of finely divided non-fibrous inorganic insulating material, an oil phenolresinous binder and an inorganic binder compound eflective at elevated temperatures.

9. A wire having a flexible insulating coating consisting of finely divided insulating oxide, an oil phenol-resinous binder and an inorganic binder compound effective at elevated temperatures.

6 10. A wire having a flexible insulating coating consisting of finely divided nonfibrous inorganic insulating material, a boron compound and an oil phenol-resinous binder.

10 11. A wire having a flexible insulating coating consisting of finely divided insulating oxide, a boron compound and an oil phenol-resinous binder.

12. A wire having a flexible insulating coating consisting of a baked layer of a mixture of finely divided non-fibrous inorganic insulating material, an oil phenol-resinous binder, an inorganic binder compound, effective at elevated temperatures and a plasticizing agent.

13. A wire having a flexible insulating coating consisting of a baked mixture of finely divided oxide, an oilphenol-resinous binder and an inorganic binder compound effective at elevated temperatures.

14. A Wire having a flexible insulating coating consisting substantially of finely divided chromium oxide, an oil phenol-resinous binder and an inorganic binder compound effective at elevated temperatures.

15. A wire having a flexible insulating coating consisting substantially of finely divided chromium oxide, an oil phenol-resinous binder and a. boron compound.

16. A wire having a flexible insulating coating consisting substantially of finely divided chromium oxide, an oil phenol-resinous binder and boric acid.

17. A wire having a flexible insulating 40 coating consisting substantially of finely divided titanium oxide, an oil phenol-resinous binder and an inorganic, binder compound eifective at elevated temperatures.

18. A wire having a flexible insulating coating consisting substantially of finely divided titanium oxide, an oil phenol-resinous binder and a boron compound.

19. A wire having a flexible insulating coating consisting substantially of finely divided iron oxide, an oil phenol-resinous binder and an inorganic compound eflective at elevated temperatures.

20. A wire having a flexible insulating coating consisting substantially of finely divided iron oxide, an oil phenol-resinous binder and a boron compound.

In testimony whereof I affix m signature.

' SAMUEL iiUBEN. 

